1. Field of the Invention
This invention relates to novel rotary valves comprising ceramic-resin composites for brass wind musical instruments.
2. Prior Art
Conventional rotary valves for the instruments have been made of a metal material such as brass. The schematic constructions of a rotary valve for brass winds are explained with reference to FIG. 3. Numeral 1 represents a casinq composed of a slightly tapering cylinder like portion 1' and terminal plates 7, 8, into which a valve body 2 is rotatably inserted. The valve body 2 is nearly columnar, and two round grooves 3, 4 extending in the direction orthogonal to the axis of the column body are bored on the opposite sides through the outer regions of the valve body 2. Valve axes 5, 6 protrude from the centers of the both end surfaces of the valve body 2. The cylinder portion 1' of the casing 1 is provided with terminal plates 7, 8 at the both ends thereof. The valve body 2 is supported by inserting the valve axes 5 and 6 into the bearings 9 and 10 which are provided at the centers of the terminal plates 7 and 8, respectively.
In the casing 1, plural (normally four) openings 11 of round shapes are provided for the flow of air. By rotating the valve body 2 to a predetermined rotation phase and then holding the valve body there, certain openings 11 are communicated to adjust the length of sound waves. Incidentally, the valve axis 5 is connected Lo a cam rod (not shown in FIG. 3). When a player of the brass wind pushes a button on the wind instrument, the valve body 2 is rotated by means of the cam rod to a predetermined position and held at the position. A plurality of such rotary valves are provided in the cylindrical tubes of the brass wind, and thus the brass wind is constructed such that the paths of air flow can be changed in multiple ways.
More specifically, the openings 11a and 11b in FIG. 3 are connected to the cylindrical tubes of a brass wind instrument, respectively. The openings 11a and 11b communicate with the groove 4 of the valve body 2, for example, in the normal position of the valve body, and air flows from the opening 11a to the opening 11b via the groove 4. The openings 11c and 11d are connected with a cylindrical tube (not shown in FIG. 3). When a button is pushed by a player, the valve body turns by 90 degrees, and connects the opening 11a to the opening 11c via the groove 4 and the opening 11d to the opening 11b via the groove 3 of the valve body. Thus, air flows through the path composed of the opening 11a, groove 4, opening 11c, cylindrical tube, opening 11d, groove 3 and opening 11b, whereby certain lowpitched tones are produced. Such constructions and mechanisms of the rotary valves do not make a large difference between the conventional brass valve and the valve of the present invention.
Since the valve bodies and casings in conventional rotary valves have been made of brass, the valve axes and holes of bearings are apt to wear into looseness in a short period of use. Moreover, rust is often produced between the valve body and casing, which impairs smooth rotation of the valve body. In addition, a brass valve body can rotate smoothly by slightly oiling the valve with a lubricating oil and by the lubricating action of the water produced on outer surfaces of the valve body through dew condensation of the moisture contained in the breath of an instrument player. Thus, the valve body sometimes fails to rotate smoothly when humidity in air is so low or temperature is so warm that the dew condensation does not take place.